1. Field
The invention relates to a method for producing composite materials containing as a first layer a foamed thermoplastic support and as a second layer polyurethane (PU), the resulting composite materials being characterised by improved foam adhesion. The invention also provides the composite systems produced by this method and their use as a component, in particular in the automotive sector.
2. Description of Related Art
The use of compositions containing aromatic polycarbonate and rubber-modified graft polymer as a compact (i.e. non-foamed) support in a composite with polyurethane is known.
A composite material made from polyurethane and a compact thermoplastic is known from EP-A 1057851 in which in order to improve adhesion the polyurethane layer contains homogeneously distributed particles having an average particle size of 1 to 10 nm, which are coated with a thermoplastic.
Furthermore, a composite material made from polyurethane and a compact thermoplastic material is known from EP-A 1055717 wherein in order to improve the adhesion between the polyurethane and the thermoplastic layer a polyurethane is used which has a residual content of free ether-group-containing reaction components of at most 400 ppm.
In the prior art structured and unstructured compact thermoplastic supports are produced in a mould. Depending on the thermoplastic used (for example glass-fibre-reinforced polypropylene or impact-modified polycarbonate), the surface of the thermoplastic support is optionally modified by priming or activation, for example. This modification of the surface of the thermoplastic support is used in particular if a highly reactive polyurethane system (i.e. having a demould time of less than 100 seconds) is used for the composite.